Lipid digestion Flashcards
What two peritoneal ligaments hold the liver between stomach and front abdominal wall?
Lesser omentum (between liver and stomach) and falciform ligament (between liver and front abdominal wall)
What are the 6 main liver functions?
Macrophages Metabolizes: carbs, lipids, proteins Stores vitamins and iron Fibroblast-like cells store vitamin A Detoxifies drugs, hormones, bacterial metabolites Secretes bile and conjugates bilirubin
What are the 4 blood pathways of the liver?
Hepatic artery - from heart to liver, O2
Hepatic vein - from liver to heart
Portal vein - from stomach, spleen, intestins to liver, no O2, nutrient-filled
Sinusoids - detox
What is in the portal area (triad) at each corner of a lobule of liver?
Hepatic artery
Portal vein
Bile canaliculus
(central vein runs through)
What is the liver acinus?
More function unit of liver
From hepatic and portal vessels:
Zone 1 with highest O2 and nutrients
Zone 3 with lowest but is where alcohol and drugs get detoxed (susceptible to toxic damage)
What is the lymphatic flow of plasma?
Sinusoids to space of Disse, located between hepatocytes and endothelium of sinusoids, then to inferior vena cava or thoracic duct
What can fibrosis lead to?
Portal hypertension
What is portal hypertension?
Back pressure of blood into portal circulation due to obstruction so varicose veins occur in places such as caput medusae (dilated abdominal veins)
What is ascites?
Excess lymph fluid build-up in peritoneal cavity from portal hypertension; drop in blood volume causes water retention
(liquid looks like beer because of albumin and can be extracted)
What’s in bile?
Bile acids/salts, phospholipids, cholesterol (end product is lecithin)
Electrolytes, melatonin (as antioxidant)
What are the biliary ducts?
R + L hepatic ducts, common hepatic duct, cystic duct, common bile duct
Main pancreatic duct
Hepatopancreatic ampulla (junction of common bile duct and pancreatic duct)
Major duodenal papilla (common bile and pancreatic juices going into duodenum)
What are gall bladder functions?
Store, concentrate, and release bile by relaxing spincter of Oddi
How can you determine if a patient has gallstones?
Abdominal ultrasound to look for sludge, gravel, stones
How can you determine if the gallbladder is contracting properly in response to CCK?
Do a scan to check for biliary dyskinesia anywhere above sphincter of Oddi
What does CCK do?
Promotes DIGESTION: gallbladder emptying, pancreatic secretion, intestinal peristalsis
Inhibits gastric emptying
What does secretin do?
Promotes HCO3 secretion from bile, pancreatic ducts, Brunner’s glands
What are gall stones?
Precipitates of cholesterol
What are gall stones caused by?
*Reduced reabsorption of bile salts in the terminal ileum
Excess absorption of water, bile salts, lecithin
Excess secretion of cholesterol
Inflammation of epithelium
Stasis of the gall bladder smooth muscle layer (increases cholesterol crystals)
What is the triad of biliary lithogenicity?
Balance of %cholesterol, phosphatidylcholine (lecithin made from phospholipids), and bile salts
What enzyme converts cholesterol to bile salts?
7-alpha-hydroxylase
What 4 things require bile?
Digestion and absorption of lipids
Elimination of endogenous and exogenous substances
Neutralization of gastric acid
Bacteriocidal activity
What is the sequence of fat digestion?
Lipases hydrolyze triglycerides into FFA
FFA transported to enterocytes via biliary micelles
FFA reconverted to TGs, then chylomicrons, then transported to blood through lacteal and thoracic duct
What enzymes does bile use to emulsify fat?
Pancreatic lipase - breaks TG chains by hydrolysis
Phospholipase A2
Cholesterol esterase
*byproducts go into micelle
Where is micelle conjugated and where is it deconjugated?
Conjugated to taurine or glycine to form bile salts in liver
Deconjugated in intestine by bacteria to form bile acids
